This invention is in the field of internal combustion engines and particularly such engines also employing steam to produce power.
It has been previously proposed to construct a six-stroke cycle engine wherein the first four strokes function as a conventional internal cumbustion engine and include an intake stroke, a compression stroke, a power stroke, and an exhaust stroke but including two further strokes before the cycle is completed wherein, after exhaust of the products of combustion from the combustion chamber, water is injected into the combustion chamber to be converted by the heat remaining therein into steam to provide a steam expansion power stroke and a following steam exhaust stroke. Such prior proposals, however, were either of complicated construction or of very low efficiency. In the case of such engines as described in U.S. Pat. No. 1,339,176, the heat of the exhausted products of combustion was entirely lost, resulting in very inefficient operation. Six-stroke cycle engines of the type shown in U.S. Pat. Nos. 1,217,788 and 2,671,311 relied on steam generating means external of the engine itself for providing the steam for a steam expansion power stroke. Obviously, such arrangements were complicated and expensive to produce and introduce more mechanisms through which heat losses are suffered. None of the prior art known to applicant proposes to recover a large part of the heat contained in the products of combustion and return that heat to the combustion chamber for vaporization of injected water during a steam expansion power stroke.